Many mobile machines have tracked undercarriages that move along the ground as the machine travels. For example, many earthmoving machines like tractors and excavators may have such undercarriages. In known undercarriage designs, many of the parts have complex geometric designs that drive considerable manufacturing costs. FIGS. 1A-1C provide examples of certain undercarriage components and their complex designs.
FIG. 1A shows a portion of a prior art link assembly 400, which serves as the flexible backbone of the endless track of an undercarriage. Link assembly 400 includes a plurality of links 401 assembled into laterally spaced pairs connected to one another at pivot joints 403. Each link 401 includes sides 402. Additionally, each of links 401 includes a roller rail 405 on which rollers (not shown) of the undercarriage ride during operation. Collectively, the roller rails 405 of links 401 form two roller rails 407 of the link assembly 400.
As FIG. 1A shows, links 401 have complex shapes. The sides 402 of links 401 have complex contours with curves, recesses, and projections. Additionally, the roller rail 405 of each link has a wide portion in the middle and laterally offset narrower portions on its ends. At each pivot joint 403, laterally offset narrow portions of the roller rails 405 of two connected links 401 sit beside one another and collectively provide a bearing surface of substantially the same width as that provided by the center portion of the roller rail 405 of each link 401. This gives each overall roller rail 407 of the link assembly 400 a substantially constant width. This also ensures that each of roller rails 407 presents a substantially continuous straight outer guide surface 412 with which outer guide flanges of the rollers can remain substantially continuously engaged.
Opposite roller rails 405, links 401 include provisions for attaching track shoes (not shown) to the links. Each link includes windows 406 in its sides 402. Below each window 406, each link 401 includes a hole 409 for receiving a bolt, as well as a nut seat 408 for receiving a nut to secure the bolt. To secure a track shoe to each link 401, the track shoe may be placed against the side of the link below the holes 409, bolts may be inserted through holes in the track shoe and the holes 409, and a nut may be secured on the bolt against nut seat 408.
FIGS. 1B and 1C show a prior art idler 414 for an undercarriage. Similar to links 401, idler 414 has a complex design. FIG. 1B provides a perspective view of the idler 414, and FIG. 1C provides a cross-section through a rotational axis of the idler 414, idler 414 includes a hub 416 and a body 418. Hub 416 is constructed of two pieces welded together in the middle. Body 418 is hollow with a cavity 420 inside it. Body 418 includes side plates 422 and a rim 424. Side plates 422 are frustoconical discs that are welded to hub 416. Side plates 422 extend away from one another as they extend radially outward from hub 416. Rim 424 may be a ring that extends around radially outer portions of webs 422. Rim 424 may be welded to the radially outer portions of webs 422. Rim 424 may include a center flange 426 flanked by a pair of tread shoulders 428. Tread shoulders 428 may be disposed radially inward of the outer surface of center flange 426. In operation, center flange 426 may sit between links 401, and tread shoulders 428 may ride on the roller rails 407 of link assembly 400.
Geometrically complex designs like those shown in FIGS. 1A-1C may provide certain benefits that are particularly important for some applications. However, these complicated designs also have certain drawbacks. For example, manufacturing components like those shown in FIGS. 1A-1C may prove undesirably expensive. Manufacturing links 401 with their offset roller rails 405 and other complex geometric features may involve expensive processes, such as forging or casting. Manufacturing the complex shapes of the webs 422 and rim 424 of idler 414 also involve expensive processes like forging or other forming processes. All of these expensive manufacturing processes may undesirably increase the cost of the undercarriage. The disclosed embodiments may help solve these issues.